Background <p>This study aims to investigate the impact of the Philosophy for Children (P4C) education program on preschool children’s executive functioning skills in an out-of-school learning environment.</p> Method <p>The study used a mixed-methods approach, combining a pre-test-post-test control group experimental design with in-depth interviews. Quantitative data were collected using the Executive Functioning Skills Scale (EFSS), developed by the researchers, while qualitative data were gathered through a Semi-Structured Interview Form. The research involved 37 children (17 in the experimental group and 20 in the control group) and 17 parents, who participated in a 16-session Out-of-School Learning Environment Philosophy for Children (OSLE-P4C) program held in various settings, including libraries, museums, and forests.</p> Results <p>Quantitative analyses conducted after the eight-week OSLE-P4C education program showed a significant improvement in the executive functioning skills of children in the experimental group (<i>p</i> &lt; 0.05). The mean total executive functioning score of the experimental group (x̄ = 52.59) was notably higher than that of the control group (x̄ = 32.85). This large effect size (η² = 0.94) supports the program’s effectiveness. The retention test (x̄ = 56.71) indicated that the gains remained evident one month after the initial assessment. Qualitative results showed that the program led to tangible, positive changes in children, particularly in socialization, creativity, attention, and planning.</p> Conclusion <p>The quantitative and qualitative findings demonstrate that the OSLE-P4C training program contributes to the development of executive function skills in preschool children. Hands-on learning and exposure to diverse environments enhanced the program’s effectiveness.</p>